Try it again if you have it in a drawer, its funky to get use to like re-training a muscle. Maybe try the Ergo Plus instead, I don't like the rubber material on the top but the added angle has my hand resting on it naturally.
I never had any problem with any mouse, it is the fact that I need to move the thumb so much. Also I might have a job which is more intensive in mouse than most people coding.
Or perhaps is that the "celtic hand" runs in my family and it is not good to use. I am afraid I will have to sell it, which I don´t particularly like because it costed me quite a lot.